[Haskell-cafe] Inlinable (>>>)

[Saurabh Nanda]

I had a similar WTF moment when I noticed that Lucid's HtmlT over IO was 2x
slower than HtmlT over Reader/Identity. Discussions over this mailing list
pointed to the lack of INLINE pragmas on various functions, like >>=

It was finally resolved via a liberal sprinkling of INLINE --
https://github.com/chrisdone/lucid/pull/67/files

Why can't GHC automatically consider *every* function as INLINABLE? Let the
GHC heuristics decide what is worthy of being inlined. What's the downside?

-- Saurabh.

On 3 Mar 2017 5:36 pm, "Matthew Pickering" <matthewtpickering at gmail.com>
wrote:

> I suspect this is because GHC will not specialise functions when used
> in other modules unless they are marked INLINABLE.
>
> Matt
>
> On Fri, Mar 3, 2017 at 11:40 AM, Joachim Breitner
> <mail at joachim-breitner.de> wrote:
> > Hi,
> >
> > Am Donnerstag, den 02.03.2017, 18:18 +0300 schrieb David Sorokin:
> >> I offer to define the functions of the Control.Category module
> >> inlinable:
> >>
> >> -- | Right-to-left composition
> >> (<<<) :: Category cat => cat b c -> cat a b -> cat a c
> >> {-# INLINABLE (<<<) #-}
> >> (<<<) = (.)
> >>
> >> -- | Left-to-right composition
> >> (>>>) :: Category cat => cat a b -> cat b c -> cat a c
> >> {-# INLINABLE (>>>) #-}
> >> f >>> g = g . f
> >>
> >> Perhaps all functions from this module should be marked by this
> >> pragma as possible.
> >
> > I am surprised that GHC does not consider these inlineable
> > automatically. Maybe it should? Would be worth investigating, if
> > someone is interested in some entry-level GHC hacking, why GHC does not
> > treat them as `INLINEABLE` in the first place. They are certainly small
> > enough, I would say…
> >
> > Joachim
> >
> > --
> > Joachim “nomeata” Breitner
> >   mail at joachim-breitner.de • https://www.joachim-breitner.de/
> >   XMPP: nomeata at joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F
> >   Debian Developer: nomeata at debian.org
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